1. Field Of The Invention
The present invention relates to control systems for automated commercial and industrial environments, such as a control system for an assembly line, and particularly to an operator interface device for an HMI (Human-Machine Interface) system that provides for simple, generic communication between an operator work station and HMI software running on a server.
2. Description Of The Related Art
Many commercial, industrial, warehouse, and manufacturing establishments resort to automation in order to reduce labor costs and increase efficiency. Automated systems often are computer-controlled. Typically, the computer will be located at a central location and will control a plurality of operator work stations distributed throughout the establishment remote from the central location.
Machines are used to move products and components from one location to another, to assemble products, to package products, and to perform other services related to the nature of the establishment. Human operators may be located at the operator work stations to operate various machines at the work stations, position components, monitor machine processes, and troubleshoot problems that may occur at the remote locations.
A typical model for such a system is the Supervisory Control and Data Acquisition Model (SCADA) model. A SCADA system customarily includes input and output signal hardware connected to the machines, a plurality of Remote Terminal Units (RTU) or Programmable Logic Controllers (PLC) connected to the hardware, a central station running HMI software connected to the RTUs or PLCs, and a communications infrastructure for communicating between the components. The signal hardware will typically include some sort of alarm, either as a horn or other audio device, or in the form of light signals r beacons, or both.
A problem with this approach is that the hardware signal devices and the PLCs or RTUs are custom selected for the particular application. PLCs, for example, were originally developed to replace systems of relays and switches in automation systems, and used simple logic circuits and “ladder logic” of the type that an electrician or electronics technician could follow and program from an electrical schematic diagram. PLCs have advanced to use block programming languages and, in some cases, structured programming languages; nevertheless, PLCs retain their circuit-based roots and still must be customized by an electrician to interface with particular hardware implementations, which is both expensive and time consuming. RTUs suffer from much the same problem.
An automotive assembly line, for example, requires multiple operator workstations, each of which requires input/output signal hardware and a PLC to interface with HMI software, such as GE Fanuc's Proficy® or Cimplicty® HMI software, Allen-Bradley/Rockwell Automation HMI, Wonderware HMI, and the like. At costs in the tens of thousands per workstation for installation of fifty to one hundred work stations per division or per plant, together with the down time when workstations require maintenance, repair, replacement, or upgrading, plant efficiency suffers.
Consequently, there is a need for a generic operator workstation unit for HMI systems that operates directly under Information Technology (IT) control without requiring custom installation. Thus, a hardware interface device solving the aforementioned problems is desired.